Building entrance protectors are used to provide telephone or cable TV lines from the telephone or cable TV company's street cables to multiple tenants of residential or commercial buildings. Typically cable pairs extend into a splice unit disposed within the housing of the building entrance protector. Telephone and cable TV lines are then provided to a line protector unit that functions to suppress transient electrical signals resulting from thunderstorms and other environmental noises. Telephone and cable TV wires are then extended to various tenant locations within the building via an internal connection unit.
Building entrance protectors typically have holes on one or more sides to allow the cables to enter into the interior or extend to exterior of the housing. According to the prior art, many building entrance protectors come with concentric knockouts of varying sizes, which allows the user to gently hammer-out the knockout portion that is closer in size to the circumference of the cable being used while leaving the bigger-sized knockouts intact. Having concentric knockouts of varying sizes has the advantage of allowing greater flexibility in the use of cables of varying diameter sizes.
Often, however, the user will find a knockout size that is close to the cable's circumference, but not of precisely the same size. The removal of the knockout portion creates a hole through which the user can extend wires or a cable from inside the housing to the outside of the housing. Often it is desired to secure the cable that extends through the hole by a strain relief bracket so that external pulling forces on the cable would not disengage wiring connections.
Typically, a strain relief assembly comprises of an outside clamping assembly that includes two half cylindrical brackets that secure the cable by covering its circumference. The two half cylindrical brackets are then fastened together by two screws located on each side of the cylindrical brackets. The strain relief assembly also includes an inside C-clamp bracket that clasps the cable and is screwed on to the inside surface of the sidewall of the housing such as a building entrance protector just next to the hole in use. This may be problematic if the knockout being used is one of the smaller ones, and the inside C-clamp bracket has to be screwed on to the next concentric knockout portion of the building entrance protector. Since the perimeter of knockout portions have small grooves dug or scored into the box, these portions are not as strong as the rest of the sidewall surface of the building entrance protector and are incapable of retaining as much stress as the rest of the building entrance protector's surface. Thus, by screwing the bracket on these knockout portions, the user runs the risk of having all the concentric knockouts being dislodged if the cable is pulled.
Thus there is a need to overcome the disadvantages of brackets that are screwed on the concentric knockouts surrounding a hole through which a cable is being extended and retained by a relief mechanism.